[coroutines] Handle get_return_object_on_allocation_failure

Summary:
If promise_type has get_return_object_on_allocation_failure defined,
check if an allocation function returns nullptr, and if so,
return the result of get_return_object_on_allocation_failure().

Reviewers: rsmith, EricWF

Reviewed By: EricWF

Subscribers: mehdi_amini, cfe-commits

Differential Revision: https://reviews.llvm.org/D31399

llvm-svn: 298891

1 files changed, 18 insertions, 0 deletions

diff --git a/clang/test/SemaCXX/coroutines.cpp b/clang/test/SemaCXX/coroutines.cpp
index 6849f0682c6..a75c2d62f91 100644
--- a/clang/test/SemaCXX/coroutines.cpp
+++ b/clang/test/SemaCXX/coroutines.cpp
@@ -634,3 +634,21 @@ float badly_specialized_coro_handle() { // expected-error {{std::experimental::c
   //expected-note@-1 {{call to 'initial_suspend' implicitly required by the initial suspend point}}
   co_return; //expected-note {{function is a coroutine due to use of 'co_return' here}}
 }
+
+struct promise_on_alloc_failure_tag {};
+
+template<>
+struct std::experimental::coroutine_traits<int, promise_on_alloc_failure_tag> {
+  struct promise_type {
+    int get_return_object() {}
+    suspend_always initial_suspend() { return {}; }
+    suspend_always final_suspend() { return {}; }
+    void return_void() {}
+    int get_return_object_on_allocation_failure(); // expected-error{{'promise_type': 'get_return_object_on_allocation_failure()' must be a static member function}}
+    void unhandled_exception();
+  };
+};
+
+extern "C" int f(promise_on_alloc_failure_tag) {
+  co_return; //expected-note {{function is a coroutine due to use of 'co_return' here}}
+}